Well covered by the above Posts.
In their natural range, there can be distance between them and the rest of the family /flock. As a result, they are very interested in maintaining contact with each other as a result, a natural chatter between each other exists. We tend to be far less concerned about where each other are since we busy with our Smart Phones.
Over the years, our Amazons have come to us sick, hurt, and/or abused. They are near silent and our greatest joy is when they open up. A loud and noisy Amazon is music to our ears. When you involve yourself with your Parrot and share in the communication you will be very surprised as just how much you miss that is happening around you and them. Whether it is a delivery to the home. Something different in the backyard or something out of place in a room, etc, etc, etc...
Enjoy the sounds of an active healthy Parrot. Join it, you will be surprised just how much joy you will get with keeping in contact.